We need a word for this technique where you get a customer to up their purchase by selling them on additional things.
We now need a word for this technique where you use irony to mock someone. ;)
The idea of presenting non-essential products to impulsive buyers at the point of payment is much more ubiquitous though: supermarkets and candy/magazines comes to mind.
I tend to respond to upselling attempts with silence and a blank stare.
With that in mind, how much is super sizing in relation to the original meal?
Anchoring would be if the suit salesman shows you a $3k suit to start out. Or more realistically say an $800 suit for your average person-not so outrageous as to offend you, but probably still out of your range, so you'll be more likely to spend $400 on a suit than if he had just started out in a more standard $300 range.